This application is not related to any other pending application.
1. Technical Field
The present invention relates to coatings and more particularly to inks. Still more particularly, the present invention relates to coatings which contain components which are odor masking, odor reducing, or perfuming.
2. Background Information
The prior art discloses the use of fragrant or scented inks for use in various packaging and novelty applications. U.S. Pat. No. 5,018,974 to Carnahan, et al., for example, discloses a publication with image areas that release an appropriate fragrance upon being colored or painted by the user. Microcapsules that contain fragrance oil for a particular fragrance associated with the image area are deposited on the image area of the substrate. Inert walls of materials such as gelatin restrain the fragrance within the microcapsules until activated. A color dispenser such as a felt tip marking pen is adapted to include a reactive agent that when applied to the image area in the normal course of coloring will cause release of the fragrance by rupturing or otherwise interacting with the microcapsules such as by diffusing into the microcapsules and replacing and releasing the oil. The reactive agent may be a solvent such as an alcohol or ketone or a surfactant contained in an aqueous solution mixed with the normal ink or paint of the marking pen. The invention enables release of fragrances in the normal course of coloring an image without requiring action such as scratching or pulling apart of the sheets on which the image is placed.
U.S. Pat. No. 5,577,947 to Malloy, et al. discloses a scented ink composition and method of printing in which a scented ink image is applied to a novelty item such as a balloon. The scented ink comprises a mixture of a conventional printing ink with a fragrant oil wherein the fragrant oil is added to the printing ink at a concentration from 4-7% by weight. After mixing, the scented ink solution is used in place of conventional printing ink in a flexographic printing press, and the press is operated in a normal fashion to print images on metalized nylon sheeting used in the manufacture of balloons. After printing the scented ink images onto the sheeting, the image is dried in a conventional manner and the matter is wrapped in polyethylene for storage until used in the manufacture of the balloons.
U.S. Pat. No. 6,123,757 to Yang, et al. discloses a fragrant ink for use in a microjet printer. This fragrant ink composition comprises an alcohol component in an amount of 1-20% by weight, an imaging component which may be a pigment used in the amount of 1-10% by weight, a fragrant agent component used in the amount of 0.05-20% by weight, and an additional ethanol component used in the amount of 2-20% by weight which reduces drying time of the ink.
A problem, however, which has attended the use of scented or fragrant ink in that the scents or fragrances may not last for extended periods of time. Particularly for packaging applications, the failure of ink to retain its scent over an extended period of time, where the package may be in storage or shipping, may seriously detract from the overall desirability of using the scented ink.
It is an object of the present invention to provide a scented ink which retains its scent or fragrance over an extended period of time.
This and other objects are met by the present invention which is a method of preparing a scented ink composition comprising the steps of first preparing a mixture which includes a resin component consisting of a water soluble polymer selected from the group consisting of acrylic, styrene-maleic anhydride, sulfonated polyester, polyamide, and polyurethane, a color component selected from the group consisting of a pigment and a dye, and a solvent component comprising water. The mixture is then agitated. An oil-based fragrance is blended into this mixture to produce a scented mixture, and is then agitated. A microemulsion of the oil-based fragrance in water is created, wherein the resin stabilizes the microdroplets of the oil-based fragrance by coating the microdroplets. Preferably, the microdroplets of the oil-based fragrance have a diameter of from about 0.1 to about 1.0 micrometers.
Also encompassed by the present invention is a scented ink composition produced by a method comprising the steps of first preparing a mixture which includes a resin component consisting of a water soluble polymer selected from the group consisting of acrylic, styrene-maleic anhydride, sulfonated polyester, polyamide, and polyurethane, a color component selected from the group consisting of a pigment and a dye, and a solvent component comprising water. The mixture is then agitated. An oil-based fragrance is blended into this mixture to produce a scented mixture, and is then agitated. A microemulsion of the oil-based fragrance in water is created, wherein the resin stabilizes the microdroplets of the oil-based fragrance by coating the microdroplets. Preferably, the microdroplets of the oil-based fragrance have a diameter of from about 0.1 to about 1.0 micrometers. It is also believed that in this composition these microdroplets will tend to be coated by the resin component.
The resin component of the ink will preferably be provided by an acrylic varnish in the amount of 15%-45% by weight of the entire composition and an acrylic emulsion in the amount of 0-30% by weight of the entire composition. The acrylic varnish has a solids content of about 20% to about 40% by weight. The solvent for the acrylic varnish is water. A general procedure for preparing this acrylic varnish is as follows. Water is added in a mill (Kady) or high speed mixer. Ammonia (21xc2x0Bxc3xa9) is added and mixed with water. The polymer is added and mixed until completely dissolved.
The acrylic emulsion is an emulsion of acrylic monomers and a water solvent. These monomers may be selected from methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyethyl methacrylate, butyl methacrylate, acrylonitrile, acrylic acid, methacrylic acid, itaconic acid, malic acid, fumaric acid, acrylic anhydride, methacrylic anhydride, maleic anhydride, itaconic anhydride, fumaric anhydride, styrene, substitued styrene, vinyl acetate, and other C.sub.1 to C.sub.12 alkyl acrylates and methacrylates. Polymerization of the above monomers takes place in situ by emulsion polymerization. Preferably, the glass transition temperature of the polymer is in the range of about xe2x88x9240xc2x0 C. to about +50xc2x0 C.
In a preferred composition, the pigment dispersion will be used in the amount of 25%-65% by weight. This pigment dispersion may be either an organic or inorganic pigment dispersion. Preferred organic pigments are phthalocyanines, azos, naphthols, and rhodamines. Preferred inorganic pigments are titanium oxide, iron oxides, and carbon black. Preferred carriers are water, acrylic resin solution, glycol, and surfactant. Preferably, the pigment particles will have a particle size of less than about 3000 nanometers. (3 micrometers). Alternatively, the color component may be a dye. Suitable dyes include acid, basic, direct, and disperse dyes.
Deionized water in the amount of 0-15% by weight will next be added to the mixture. A wax compound which will preferably be a polymeric wax selected from polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), or a blend of polyethylene (PE) and polytetrafluoroethylene (PTFE) will then be added to the mixture in the amount of 3%-6% by weight. A defoamer which will preferably be mineral oil, silicone, polysiloxane, or silicone-free will then be added to the mixture in the amount of 0.2%-0.5% by weight after which the mixture will be added to a mixing vessel and blended under high speed mixing preferably for at least about 15 minutes. An oil based fragrance is added last, slowly and under high speed mixing, to affect a emulsification of the fragrance in the water system. Suitable oil based fragrances include chocolate, cherry, lemon, peppermint, coffee and similar fragrances. During the manufacturing process, a microemulsion of the oil-based fragrance in water is created via high speed mixing. The microdroplets of the fragrance are stabilized by the high solids content of the acrylic varnish/acrylic emulsion system, whereby the resin molecules coat the microdroplets of the fragrance to ensure stability and long lasting effect of the scent. The process is preferably carried out at room temperature and at normal atmospheric pressure. The viscosity of the final ink is preferably in the range of 20-35 seconds as measured in a #4DIN Cup. The pH will preferably be between 8.0-9.5. Both viscosity and pH are typical for water based flexographic inks.
The method of the present invention is further described with reference to the following examples.